With the increased popularity and usage of the Internet and World Wide Web, computers are used to distribute data files (which are often large in size) over digital networks. These data files include electronic mail addressed to individuals and/or groups of people, postings for electronic bulletin boards (e.g. the usenet), pages from World Wide Web servers, audio files (encoded with MP3), video files, digital images, digitized books and diagrams, and updates and errata of digitized books and other documentation. In general, network computing is well known. For example, see U.S. Pat. No. 5,371,852 to Attanasio et al. issued on Dec. 6, 1994. This patent is herein incorporated by reference in its entirety.
For example, an insurance company may transmit many different forms of digital data to their insurance agents. The company may produce training videos and audio tapes which are digitized into video and audio data files. It may also publish its rules and regulations in digital form as web pages or digital books. Updated actuarial tables and insurance prices may be transmitted periodically. And the insurance company may use e-mail to communicate with the agents as a whole or individually. The size of these data files can vary greatly and clearly, some data files are more important than others and need to be transmitted at a higher priority or otherwise in a controlled manner. Currently, much of the prior art does not use the priority and size of documents to determine how the documents are transmitted over a network.
While many techniques and tools are used in scheduling real-time tasks for computer central processing units (CPUs), these techniques have not been applied to scheduling transmissions of data files over a network. In a real-time operating system, a computer has many jobs to run, each of which has a release time, deadline, worst-case running time, and optionally a period. The scheduler of the real-time operating system examines these job constraints and devises a schedule which allows the computers CPU(s) to operate the tasks to completion and meet the release and deadline constraints if the constraints taken as a whole are feasible. Some real-time operating system schedulers also have the ability to discard jobs on a priority basis in the event that a feasible schedule cannot be computed for the entire job set. Two well known scheduling algorithms for computing a real-time job schedule are the Earliest Deadline First (EDF) algorithm and the Rate Monotonic (RM) algorithm.